Technology gives doctors better view of tumors

11/10/2000 - Theres only so much about a body a CT can show. Even PET scans, with their glowing functional images, have their limitations.

But take a black-and-white image from the CT and digitally lay over it the dotted PET pictures in a double dose of technology and you are given the most accurate roadmap to a tumor possible.

Thanks to six years of collaborative development between Vanderbilt University Medical Center and an Israel-based company, since purchased by GE Medical Systems, that kind of guidance is available in one system called functional anatomical mapping, nicknamed Hawkeye.

James Patton, Ph.D., professor of Physics and Radiology, and program director of Nuclear Medicine Technology, and Dr. Martin P. Sandler, professor and chairman of the department of Radiology and Radiological Sciences, started developing the new technology with Elscint, a Israeli imaging company in 1996. GE bought the rights to the technology from Elscint and Vanderbilt remained the lead investigational institution.

Since Hawkeye was approved by the Food and Drug Administration in June 1999, Vanderbilts Hawkeye, the first in the United States, has been used in the treatment of more than 100 cancer patients whose tumors could not be pinpointed with standard imaging systems  PET or SPECT scans. Doctors altered the course of therapy in about 35 percent of those patients due to the better look Hawkeye provided, Patton said.

Without the new mapping system, surgeons would have had to explore the patients cancer surgically.

Hawkeyes advantage doesnt come from more powerful imaging systems. In fact, patients receive more definitive diagnostic tests before the Hawkeye is employed, according to Sandler.

However, CT scans are not great for staging tumors, Sandler said. And PET images lack the anatomical landmarks found on CTs.

Weve married the two technologies, Sandler said. Hawkeye uses the CTs X-ray slices to see the anatomy and the metabolic tracers from the PET scan to see the hot spot of a tumor.

Patients undergoing Hawkeye receive an injected radioisotope, just as they would for a traditional PET scan, Sandler said. While lying on the Hawkeye table  which resembles a typical PET or CT table  for about 40 minutes, the hybrid machine performs a CT of the cancerous area and a PET scan. Hawkeye then merges the two images, laying the PET image on top of the anatomy.

In the June issue of Diagnostic Imaging, Sandler, Patton and Dr. Dominique Delbeke, associate professor of Radiology and Radiological Sciences, report one case in which Hawkeye located a metastatic abdominal tumor on the spleen and prevented exploratory surgery. Another patients non-Hodgkins lymphoma was accurately staged because the combination of images located a metastasis in lymph nodes above the patients diaphragm  metastasis above the diaphragm would have indicated a stage III tumor and would have resulted in different therapy.

Not only will Hawkeye provide more accurate images, it will do so cheaper, Sandler says. While CT and PET machines cost about $1.2 million, the hybrid costs $750,000.

But perhaps the systems biggest positive, Sandler said, is that its home-grown technology resulting in a staff thats been acquainted with it since inception. Its one thing to go out and buy technology. Its another thing to develop it yourself, he said.